The present invention generally relates to motion control apparatus and in particular brakes. Specifically, the present invention relates to brakes suitable for use with a track to brake motion such as linear motion, and more specifically relates to linear motion brakes that have improved piston life and that are adjustable.
The popularity of linear motion devices in the machine tool, semiconductor, and medical industries has been increasing as the result of their ability to move a load in a linear movement direction to a position with extreme accuracy and at very high speeds. However, problems have been encountered in stopping linearly moving loads especially in the event of a power outage. Specifically, as movement and positioning of the load is dependent upon current being supplied to the linear motor, loads carried by linear motion devices will move under gravitational and/or inertia forces in the event that current is interrupted to the linear motor such as the result of a power outage. This problem is also enhanced in linear motion devices because of the use of high performance linear bearings, which minimize sliding friction. Prior workers have devised a brake that cures the above deficiencies and that works with remarkable reliability and precision, see U.S. Pat. No. 6,460,678 to Henk et al.
Prior art devices have utilized a one piece piston assembly to accomplish braking motion. A one piece piston assembly may apply undesirable forces to piston components.
Also, it is desirable to be able to adjust the relative position of actuator elements of friction facings to compensate for manufacturing tolerances and/or friction facing wear.
Thus, a need exists for a brake for stopping linearly moving loads and especially for use with linear motion devices and particularly for use in stopping linearly moving loads that reduces stress on piston parts and that is adjustable.